Novel pro-survival functions of the kruppel-like transcription factor Egr2 in promotion of macrophage colony-stimulating factor-mediated osteoclast survival downstream of the MEK/ERK pathway

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Abstract

Determining the underlying mechanisms of macrophage colony-stimulating factor (M-CSF)-mediated osteoclast survival may be important in identifying novel approaches for treating excessive bone loss. This study investigates M-CSF-mediated MEK/ERK activation and identifies a downstream effector of this pathway. M-CSF activates MEK/ERK and induces MEK-dependent expression of the immediate early gene Egr2. Inhibition of either MEK1/2 or inhibition of Egr2 increases osteoclast apoptosis. In contrast, wild-type Egr2 or an Egr2 point mutant unable to bind the endogenous repressors Nab1/2 (caEgr2) suppresses basal osteoclast apoptosis and rescues osteoclasts from apoptosis induced by MEK1/2 or Egr2 inhibition. Mechanistically, Egr2 induces pro-survival Blc2 family member Mcl1 while stimulating proteasome-mediated degradation of pro-apoptotic Bim. In addition, Egr2 increased the expression of c-Cbl, the E3 ubiquitin ligase that catalyzes Bim ubiquitination. M-CSF, therefore, promotes osteoclast survival through MEK/ERK-dependent induction of Egr2 to control the Mcl1/Bim ratio, documenting a novel function of Egr2 in promoting survival.

Original languageEnglish (US)
Pages (from-to)8055-8064
Number of pages10
JournalJournal of Biological Chemistry
Volume283
Issue number12
DOIs
StatePublished - Mar 21 2008

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ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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